September 29, 2026 / By rachel
How do you turn a 35-metre stone barn into a comfortable home when it climbs more than two metres from one end to the other, its historic character must be protected and opportunities for adding windows are decidedly limited?
For week 30 of our #40Projects40Weeks series, we are returning to Duke’s Barn in Monmouthshire, where the restrictions that made the conversion challenging also inspired some of its most distinctive ideas.
A Very Long Way from One End to the Other
The clients lived in London and wanted to transform one of Wales’s longest field barns into a weekend retreat that might eventually become their permanent home.
At 35 metres long, with a 2.15-metre difference between its lowest and highest points, this was never going to behave like an ordinary house. Rather than attempting to flatten out its character, RRA used the changing ground level to organise the interior into four connected zones, rising from a lower living room through the kitchen and dining area to the bedrooms and utility spaces beyond.
The threshing bay remained the heart of the building, with its tall openings glazed to preserve the sense of space and bring daylight deep inside.
Borrowing Daylight
Because new openings were restricted, every available ray of natural light had to work hard.
Translucent glass doors gave the bedrooms privacy while allowing light to travel onwards, and glass panels within the mezzanine floors carried daylight into the living areas below. Open-tread steel staircases were designed to feel visually light, while a dedicated lighting scheme picked out the stone walls, oak trusses and purlins after dark.
The result was contemporary without trying to disguise the building it occupied. New steel and glass elements sat clearly alongside the old structure, allowing both to be appreciated.
A Courtyard Instead of a Garden
The barn stands within a sensitive rural landscape close to the ruins of White Castle. Extending a domestic garden into the surrounding fields was not permitted, so the existing courtyard had to accommodate parking as well as outdoor living.
This constraint helped keep the conversion closely connected to its agricultural origins. Rather than surrounding the barn with lawns, fences and other suburban features, the landscape remained largely undisturbed and beautifully rural.
When the Build Became Complicated
Historic buildings rarely provide entirely straightforward projects, but this one brought more complications than most. Work took place during the foot-and-mouth outbreak, when rural access restrictions and additional precautions caused delays, and the main contractor also ceased trading before the conversion was complete.
Determined to keep the project moving, the clients employed the individual trades directly. It was an unconventional way to reach the finish line, but the completed barn went on to become an example of how thoughtful conversion can give a historic agricultural building a new purpose without erasing the qualities that made it special.
Details of Duke’s Barn and it’s conversion were later included in Cadw and Monmouthshire County Council’s guide, Converting Historic Farm Buildings in Wales: A Guide to Good Practice, including three images on the cover.
Download Part 1 of the Cadw guide and Part 2.
Explore the Duke’s Barn project.
This project is part of our #40Projects40Weeks series, celebrating 40 years of RRA Architects and the people, places and occasional unexpected challenges that have shaped our work.
About RRA Architects
Established in 1986, RRA Architects works across all sectors and provides architectural services from initial feasibility and design through to completion. We work nationally, with projects primarily across Gloucestershire, Herefordshire, Shropshire, Worcestershire, the Cotswolds, the West Midlands, South West and South Wales.